episode40

040 The Role of Hair Cells in Hearing

Leslie Samuel IBTV, Physiology, Sense Organs 78 Comments

Do you ever wonder what happens to the hair cells inside our ears as we hear sound? What role do these tiny hairs have in hearing?

Watch this short movie as Leslie explains clearly and vividly enough for us to understand the main role of these tiny hair cells as sound enters our ears.

Enjoy!

Transcript of Today’s Episode

Hello and welcome to another episode of Interactive Biology TV where we’re making Biology fun!  My name is Leslie Samuel and in this episode, Episode 40, I’m going to talk about the role of hair cells in hearing. So, let’s get right into it.

In Episode 39, we looked inside the cochlea to see what happened in response to sound. What we said was, in response to sound, the basilar membrane vibrated up and down, and this is the basilar membrane, which causes the Organ of Corti, which is this section here, to vibrate up and down, causing the tectorial membrane to move in a windshield wiper-like fashion that causes these hair cells to bend, the stereocilia, and the hair cells bend, causing a signal in the auditory nerve that then goes to the brain.  The brain says, “Okay that is sound,” and you hear it.

What we’re going to do today is we’re going to look specifically at what happens inside these hair cells, specially the inner hair cells which are directly responsible for the signal being sent to the brain that results in the sound that you are hearing.

So, let’s look at what happens inside those hair cells.  All right, so, I’m going to draw a hair cell.  Let’s say this is my hair cell right here. On the hair cell, I have stereocilia.  Now, this stereocilia occur in pairs: we have a long one and a short one.  In the short one, we have potassium channels so, that’s the potassium channel right here.   But, what’s interesting is that the long hair cell is mechanically connected to the short hair cell via that gate. Now, as you can imagine, when the tectorial membrane moves down on this hair cell, that causes the hair cell to bend.  So, let’s say this hair cell, the long hair cell, bends in that direction.  What is that going to do to these channels?  That’s going to cause these channels to open.  Now, these channels are mechanically-gated potassium channels.  They’re not extremely selective to potassium but, for this purpose, we’re going to look at what it does with the potassium ions.

Now, in the fluid that’s surrounding these stereocilia, we have endolymph. An endolymph is very rich in potassium ions.  So, let’s say we have potassium ions, K+, all around here.  When these mechanically-gated channels open, that is going to cause potassium ions to flow into the hair cells.  What is that going to do to the membrane potential (Em) ?  That is going to increase the membrane potential. Once the membrane potential increases, something else happens.  We have calcium ions that are also outside the cell. When that membrane potential increases, potassium is in here that’s going to cause calcium channels, voltage-gated calcium channels to open and calcium is going to rush into the cell.

Now, if you can remember when we spoke about neurotransmitter release, we said that calcium ions are the trigger that causes the neurotransmitter release in axon terminals.  This is the exact same thing that happens.  We have neurotransmitters in vesicles here and those neurotransmitters are then going to be released, and as I showed in the previous picture, this is connected to the auditory nerve, and that sends signals to the brain.

That’s all the content for this video.  I hope you learned a lot.  If you have any questions, go ahead and leave them in the comments below. That’s it for now, and I’ll see you in the next one.

Comments 78

    1. Post
      Author
    1. Post
      Author
  1. katherinependragon

    These vids are great. Have you thought about making a vid about the pathway sound takes from Cranial nerve VIII to the auditory cortex? That’s the part that really confuses me!

  2. InteractiveBiology

    @katherinependragon I actually haven’t looked at that process personally. Also, I’ve finished with the nervous system for now. Trying to get through a bunch of different topics in sequence. That might be something to look at the next time I go through the Nervous System in more detail, but that won’t be for a long while.

  3. InteractiveBiology

    I actually haven’t looked at that process personally. Also, I’ve finished with the nervous system for now. Trying to get through a bunch of different topics in sequence. That might be something to look at the next time I go through the Nervous System in more detail, but that won’t be for a long while.

  4. InteractiveBiology

    I actually haven’t looked at that process personally. Also, I’ve finished with the nervous system for now. Trying to get through a bunch of different topics in sequence. That might be something to look at the next time I go through the Nervous System in more detail, but that won’t be for a long while.

  5. InteractiveBiology

    I actually haven’t looked at that process personally. Also, I’ve finished with the nervous system for now. Trying to get through a bunch of different topics in sequence. That might be something to look at the next time I go through the Nervous System in more detail, but that won’t be for a long while.

    1. Post
      Author
  6. Djalitana

    does the potassium channel opens because of the bending of the stereo cilia and has nothing to do with osmotic pressure? if enough potassium rush in why the cell need still calcium to rush into the cell? thank you very much.

  7. Djalitana

    does the potassium channel opens because of the bending of the stereo cilia and has nothing to do with osmotic pressure? if enough potassium rush in why the cell need still calcium to rush into the cell? thank you very much.

  8. LittleDanzig

    I’m learning a lot from these lessons! My teacher’s lectures + your lecture = better understanding! Don’t ever cease to strive for increasing your communication talent! Simplicity is key!

  9. LittleDanzig

    I’m learning a lot from these lessons! My teacher’s lectures + your lecture = better understanding! Don’t ever cease to strive for increasing your communication talent! Simplicity is key!

  10. Eric Humphries

    I’m learning a lot from these lessons! My teacher’s lectures + your lecture = better understanding! Don’t ever cease to strive for increasing your communication talent! Simplicity is key!

  11. Eric Humphries

    I’m learning a lot from these lessons! My teacher’s lectures + your lecture = better understanding! Don’t ever cease to strive for increasing your communication talent! Simplicity is key!

  12. InteractiveBiology

    Thank you for your interest in our Biology videos. Unfortunately, Leslie is too busy at the moment to answer any Specific Biology questions. He has many to work on, so stay tuned for more.

  13. Djalitana

    second watch answered my question, without calcium ions no neurotransmitter release. the ability of the hair cells in transmission of sound is varies according to their distance to the auditory nerve? thanks

  14. Djalitana

    second watch answered my question, without calcium ions no neurotransmitter release. the ability of the hair cells in transmission of sound is varies according to their distance to the auditory nerve? thanks

  15. InteractiveBiology

    @Djalitana Unfortunately, Leslie is unavailable to take questions as he has no time to help. In the meantime, you can go to our FB fan page, post your questions, and your fellow readers, followers, and fellow enthusiasts in Biology may find time to answer them.

  16. InteractiveBiology

    Unfortunately, Leslie is unavailable to take questions as he has no time to help. In the meantime, you can go to our FB fan page, post your questions, and your fellow readers, followers, and fellow enthusiasts in Biology may find time to answer them.

  17. InteractiveBiology

    Unfortunately, Leslie is unavailable to take questions as he has no time to help. In the meantime, you can go to our FB fan page, post your questions, and your fellow readers, followers, and fellow enthusiasts in Biology may find time to answer them.

  18. InteractiveBiology

    Unfortunately, Leslie is unavailable to take questions as he has no time to help. In the meantime, you can go to our FB fan page, post your questions, and your fellow readers, followers, and fellow enthusiasts in Biology may find time to answer them.

    1. Post
      Author
  19. SpeedySpod

    what’s the neurotransmitter? Possibly glutamate and ‘unknown substance’ – would you happen to know???

  20. kmac0258

    I really enjoy these and they really help me to learn. is there a possibility of him continuing the senses and doing taste and smell too?

  21. green5sing

    Thank you so much! I was so lost in my Audiology class until I watched your videos (36-40)! You do such an awesome job of explaining things so that people can understand it!

  22. green5sing

    Thank you so much! I was so lost in my Audiology class until I watched your videos (36-40)! You do such an awesome job of explaining things so that people can understand it!

  23. green5sing

    Thank you so much! I was so lost in my Audiology class until I watched your videos (36-40)! You do such an awesome job of explaining things so that people can understand it!

  24. TshegoTT

    Thank you very much for the video. Please make a video on the relation between the outer hair cells and otoacoustic emissions (or just the generation of otoacoustic emissions in general). Thank you.

  25. TshegoTT

    Thank you very much for the video. Please make a video on the relation between the outer hair cells and otoacoustic emissions (or just the generation of otoacoustic emissions in general). Thank you.

  26. TshegoTT

    Does anyone know where I can get a video/article which clearly explains how outer hair cells help generate otoacoustic emissions (OAEs) and/or how the reflection of incoming waves occur? Thank you.

  27. TshegoTT

    Does anyone know where I can get a video/article which clearly explains how outer hair cells help generate otoacoustic emissions (OAEs) and/or how the reflection of incoming waves occur? Thank you.

  28. scarletwomannedm

    As a student getting ready to take my state board exam for Cosmetology this is a fascinating mini-lecture. All of your videos have helped me to understand anatomy and biology better (especially the parts on the Integumentary System–which for the Cosmetology field is obviously the most important to be studying and understanding) They have kept me interested and you made it fun! Great job!!

  29. Kin Shek

    As a patient of labyrinthitis, been dizzy for 24/7 for a year Now. Could you explain the hair cells in semi circular canals and the importance for balance and sense of space. Thx

  30. Sreelakshmi V A

    Can you explain what happens in tectorial membrane in response to the vibrations in organ of corti???

  31. Leeann Gooding

    omg thank you so much for this video….i kept reading that k+ gates open and cell is depolarized and i couldnt understand why but its because endolymph is rich in K+ so gradient is higher outside cell ….thank you thank you

  32. Cic

    Hi!
    Thank you so much! This helped me understand the IHC more than my textbook had. I would second in asking for a video on the vestibular system, if theses are still running. It would be fantastic!
    Thanks, again!!

Leave a Reply

Your email address will not be published. Required fields are marked *